The application of ultrasonic solvent extraction and solid phase microextraction for the honey characterization

Doprinos pčela i okoliša košnice isparljivim spojevima meda određen je pripravom saharozne probe (pčele u zatvorenoj košnici hranjene su saharoznom otopinom). Identificirani spojevi su srodni sastavu epitelnih voskova i voskova u košnici, a manje feromonima pčela. Toplinski tretman probe na 80 oC i uskladištenje 365 dana omogućilo je praćenje nastanka artefakata koji se mogu pojaviti u medu. Rezultati istraživanja uzoraka meda (kadulja, lavanda, vrba i amorfa) su izrazito ovisni o primijenjenoj metodi ekstrakcije sa značajnim kvalitativnim i kvantitativnim razlikama između ekstrakata vršnih para (bez otapala, HS-SPME) i ultrazvučnih ekstrakata s organskim otapalima (USE). Vršne pare su sadržavale više isparljive spojeve manjih molekulskih masa. USE tehnika omogućuje ekstrakciju poluisparljivih i vodotopljivih spojeva, posebice benzojeve, vanilinske i feniloctene kiseline. Upotreba ultrazvučne vodene kupelji (metoda neizravne sonifikacije) sa smjesom otapala (pentan : dietil-eter 1 : 2 v/v) pokazala se najprikladnijom za ekstrakciju svih uzoraka meda. S druge strane, ekstrakcija nepolarnih spojeva s pentanom, a potom ekstrakcija s polarnijim dietil-eterom omogućila je detaljniju analizu. Upotrebljene tehnike su komplementarne, a upotreba samo jedne od navedenih tehnika ne daje potpuni uvid u sastav spojeva meda te bi se mogli donijeti pogrešni zaključci, osobito kod identifikacije markera botaničkog porijekla meda.Contribution of the honeybees and hives environment to volatile honey compounds is determined by preparing saccharose probe (the bees in closed hive were feeded with saccharose solution). Identified compounds were similar to cuticular and comb waxes and less to bee pheromones. Thermal treatment of the probe at 80 oC and 365 days storage enabled investigation of artefacts formation that may occur in honey. The results of honey (sage, lavender, willow and amorpha) investigation are highly dependent on the applied extraction method with significant qualitative and quantitative differences among headspace extracts (HS-SPME) and ultrasonic solvent extracts (USE). The headspace contained high volatile compounds with lower molecular masses. USE enabled the extraction of semi-volatile and water-soluble compounds, particularly benzoic acid, vanillic acid and phenyllactic acid. The application of ultrasonic water bath (indirect sonification) with the solvent pentane : diethyl ether 1 : 2 v/v was suitable for all the samples. On the other hand, the extraction of nonpolar compounds with pentane and thereafter extraction with more polar diethyl ether enabled more detailed analysis. Applied techniques are complementary and application of only one of them does not provide complete insight in the honey composition and wrong conclusions can be drawn, particularly regarding identification of the honey botanical origin markers